Optimise Loop Check (landing screen)

[NexusQuile]

Removes iteration over waypoints to determine whether they loop. The loop index is always stored in the last waypoint.

[inorton]

This is a good change, and if I were maintaining the game itself I'd pull it in, but I dont think it will make a great deal of difference at runtime at all, and could make syncing to/from the sdk or other mods harder.